In the run-up to the action the public were urged to report material that breached counter terrorism laws or other criminal offences. This led to a four-fold increase in the number of public referrals to the police.

Among the items referred were propaganda films, terror training manuals and videos and publications glorifying or supporting terrorism and extremism.

This included material from Daesh, Boko Harem and other international terrorist organisations, as well as extreme right wing groups. Also found were a number of social media accounts linked to terrorists and extremists.

The operation was led by the UK police Counter Terrorism Internet Referral Unit (CTIRU) who work all year round to identify and refer illegal and harmful online content.

The operation was supported by Europol and other international law enforcement agencies; internet industry partners, as well as civil society and third sector organisations.

Starting at 07.00 on Friday 15th April and wrapping up 19.00 on Saturday, a total of 1953 items were referred by the CTIRU for potential removal. This is in addition to the 162,447 pieces the team have already removed since 2010.

At the same time, a series of engagement events took place at New Scotland Yard to encourage communities and partners to share ideas about how to better encourage reporting via the red STOP button.

The UK police senior national coordinator for counter terrorism Deputy Assistant Commissioner Helen Ball said: “As well as being pernicious and deeply offensive, online terrorist and extremist content goes a long way to encourage, motivate and even direct action that can kill, maim and cause great harm.

“Therefore, tackling online terror and violent extremism is of significant importance to public safety.

“We are delighted this action was supported by our counterparts at Europol and other international law enforcement agencies, as this is a truly international challenge.

“We will continue to work with them and our partners in the internet industry and the public to stop this harmful and illegal presence online in order to help prevent tragedies occurring in the future.”